Method for growing silicon single crystal

ABSTRACT

A method for growing silicon single crystal uses as materials, silicon granules prepared by the silane process and having a residual hydrogen concentration of 7.5 wtppm or less, silicon granules prepared by the trichlorosilane process and having a residual chlorine concentration of 15 wtppm or less. In the case where such silicon granules are used, a bursting phenomenon does not occur when the silicon granules are melted. As a result, there is no scattered matter due to the bursting phenomenon, whereby the growth condition of the single crystal is not disturbed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method for growing a silicon single crystalusing silicon granules.

2. Description of Related Art

As a method for growing a silicon single crystal, the Czochralski methodis well known, wherein silicon raw materials are put in a crucible madeof quartz and are melted, then a silicon seed crystal is soaked into theliquid silicon and is pulled up while being rotated, thereby growingsilicon single crystal at the lower end of the seed crystal.

As silicon raw materials to be put in the crucible in the first place,lumps of shattered poly crystal are often used. In consideration of thedecrease of volume with the melting, at first, lumps of the material areheaped in the crucible. As the melting proceeds, lumps of the materialbecome engaged in the form of a bridge. Accordingly, there is a problemin that the bridge collapses to scatter the liquid silicon, or thequartz is warped.

In order to solve the difficulties mentioned above, silicon granules areused as silicon raw materials (to be described as the initial chargesilicon materials) to be put in the crucible in the first place. In thecase where the silicon granules are used as the initial charge siliconmaterials, the difficulties described above are solved. Moreover, sincethe rate of filling can be made larger as compared with that of the lumpmaterial, cost per chip can be reduced. It also is easily dealt with,for its volume is smaller compared with that of the lump material.

When the silicon materials put in the crucible are melted, the volume isdecreased. In order to make the best use of cubic contents of thecrucible, additional silicon materials (to be described as charge upsilicon materials) are supplied into the crucible and melted. As themethods for supplying charge up silicon materials, a method forsupplying and melting cylinder shape silicon materials (Japanese UtilityModel Application Publication No. 50-11788, 1975) or a method forsupplying and melting lump silicon materials by using a special tool(Japanese Patent Application Laid-Open No. 50-11788, 1975) is wellknown.

In the case where the cylinder shape silicon materials are used, thereare difficulties in that the crucible is broken down and the liquidsilicon is leaked when too much of the materials are put in and in thatthe liquid silicon is boiled when the materials and the liquid siliconare left alone separately. Also, in the case where the lump siliconmaterials are used, since the liquid silicon is scattered when thematerials are supplied into the liquid silicon, the surface of theliquid silicon is temporarily solidified and after that, the materialsare supplied. But there is a in that the crucible is broken down and theliquid silicon is leaked during solidification.

In order to solve the difficulties described above, sometimes silicongranules are used as charge up silicon materials. In the case wheresilicon granules are used for the purpose, this difficulties describedabove are solved.

In order to grow the silicon single crystal successively while a seedcrystal is pulled up, it is necessary to supply the silicon materialsinto the crucible corresponding to the growth volume of the singlecrystal, since the crucible volume has its own limit. Also the supply ofthe silicon materials (to be described as additional charge siliconmaterials) must be carried so as not to change the growth condition.

For this reason, in the conventional example, by providing inside of thecrucible another crucible or a cylinder having an opening for flowingthe liquid silicon, the surface of the liquid silicon can be dividedinto two regions including an inner region for pulling up the singlecrystal and an outer region for supplying silicon materials (JapanesePatent Application Laid-Open No. 57-183392, 1982 and No. 47-10355,1972). These methods intend to reduce as much as possible the effect ofwave motion, dust, temperature change and so on of the surface of theliquid silicon, accompanying the supply of the materials, exerted uponthe inner region as the crystal growth region. Also as the additionalcharge silicon materials, lump shaped silicon materials which are thebroken poly crystals silicon are widely used.

Since the shape of the lump silicon materials described above is notfixed, there is a difficulty in that the material supplying portion iseasy to get clogged as the materials become engaged in the state of abridge. Hereupon, in order to solve the difficulty, sometimes silicongranules are used as additional charge silicon materials.

In the case where the silicon granules are used for initial charge andcharge up, however, there is a problem in that scattered matteraccumulates on the surface of the crucible due to the explosionphenomenon which occurs when the silicon materials are heated up toimmediately before the melting temperature, and the accumulated matterdrops on the surface of the liquid silicon, disturbing the crystalgrowth condition to produce faulty crystal.

Furthermore in the case where the silicon granules are used asadditional charge, materials scattered matter drops into the innerregion (the single crystal growth region) or onto the crystal growthsurface due to the same explosion, disturbing the crystal growthcondition to induce faulty crystal.

SUMMARY OF THE INVENTION

FIGS. 1(a), 1(b), 1(c) are explanatory views of the bursting phenomenonof silicon granules prepared by the silane process, which the inventorslearned as a result of experiment and investigation. In the silaneprocess, as shown in FIG. 1(a), granules successively grow up as aresult of combination a silicon on the surfaces thereof with silicon ingas surrounding them. In this process of growth, however, hydrogen (H)also combines with silicon, thereby H is taken in a granule, and on thesurface of the granule, undissociated hydrogen is absorbed in a form ofSi--H or H--Si--H.

In such a process of growth of a granule, a granule combines with anyother granule. As shown in FIG. 1(b), in a gap among combined granulesA, B and C, undissociated hydrogen atoms which are absorbed on thesurface of granules are in the state of being confined. When such amaterial is heated, as shown in FIG. 1(c), undissociated hydrogen atomson the surface of the granules or confined inside of the granules arereleased as hydrogen gas (H₂). When the material is in such a state justprior to melting and when a coupling force between granules is reducedas a result, it is considered that the granule explodes into pieces ofgranules due to the rapid expansion of hydrogen gas and that they enteronto the inner region of the crucible or into single crystal growthsurface as scattered matter.

The inventors learned that the bursting phenomenon of the materialitself caused in silicon granules just prior to its melting, is closelyrelated to the hydrogen concentration (to be described [H]) in thesilicon granules prepared by the silane process, and that the burstingphenomenon remarkably declines when [H] is below a prescribed value. Theinventors also leaned that the chlorine concentration (to be described[CL]) in the silicon granules prepared by the trichlorosilane processhas the same effect as [H].

In the method for growing silicon single crystal of the presentinvention, silicon single crystal is grown by using silicon granulesprepared by the silane process, wherein [H] is 7.5 wtppm or less, orsilicon granules prepared the trichlorosilane process, wherein [CL]) is15 wtppm or less. Briefly, silicon granules having [H] or [CL] asdescribed above can be used for any, or two, or all of initial chargesilicon materials, and charge up silicon materials, additional chargesilicon materials.

A primary object of the present invention is to provide a method forgrowing silicon single crystal capable of solving difficulties whichoccur when using cylinder shape or lump shape silicon materials, byusing silicon granules.

The more specific object of the present invention is to provide a methodfor growing silicon single crystal capable of repressing the burstingphenomenon by controlling [H] or [CL] to be the value above mentioned.

Another object of the present invention is to provide a method forgrowing silicon single crystal capable of preventing the scatteredmatter from dropping down on the surface of the liquid silicon, andpreventing the crystal growth condition from being disturbed.

Still another object of the present invention is to provide a method forgrowing silicon single crystal capable of producing normal siliconsingle crystal.

A further object of the present invention is to provide a method forgrowing silicon single crystal capable of reducing [H], by heatingsilicon granules in the atmosphere of an inert gas.

A still further object of the present invention is to provide a methodfor growing silicon single crystal capable of reducing [CL], byquickening the deposition speed of silicon granules prepared by thetrichlorosilane process.

Another object of the present invention is to provide a method forgrowing silicon single crystal capable of reducing a bad effect upongrowth condition by supplying additional charge silicon materials into acrucible from several positions, thereby reducing the degree oftemperature drop of the liquid silicon.

The above and further objects and features of the invention will morefully be apparent from the following detailed description andaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a), 1(b) and 1(c) is an explanatory view of the burstingphenomenon of silicon granules prepared by the silane process,

FIG. 2 is a graph showing a relationship between hydrogen concentration([H]) or chlorine concentration ([Cl]) in silicon granules and thepresence of scattering,

FIG. 3 is a sectional view of an apparatus for reducing the residualhydrogen concentration in silicon granules,

FIG. 4 is a graph showing a diffusion coefficient of hydrogen versustemperature change in a silicon granule,

FIG. 5 is a graph showing the [H] change of a center of a silicongranule as time passes when the silicon granule is heated,

FIG. 6 is a graph showing the effect which heat treatment temperatureand treatment time exert on scattering,

FIG. 7 is a graph showing a relationship between the deposition speed ofsilicon granules and residual chlorine concentration,

FIGS. 8 and 10 are sectional views showing an apparatus for carrying outa method for growing silicon single crystal of the present invention,and

FIGS. 9 and 11 are graphs showing a relationship between phase angle ofa crucible based a supply pattern of silicon granules into the crucibleand temperature of liquid silicon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a graph showing the relationship between [H] or [Cl] insilicon granules material and the presence of scattering when siliconsingle crystal is produced. In the graph, the abscissas as shows [H] (byfusion gas-chromatography) and [Cl] (by neutron activation analysis) andthe ordinates axis shows the presence of scattering. In the graph, ◯ and□ shows no scattering, and symbols and show scattering, respectively. Asis obvious from the graph, in the case where [H] is 7.5 wtppm or less or[Cl] is 15 wtppm or less, there is no scattering in the growing process,thereby it is possible to produce normal silicon single crystal.

Incidentally, in the case where silicon granules are prepared by thesilane process, silane gas SiH₄ is decomposed at the temperature600°˜800° C. on the surface of powdered silicon seeds introduced in abell jar and the powdered seeds grow into granules. The prepared silicongranule has a structure in which fine single crystal particles gather,and usually undissociated hydrogen (H) is taken in to the degree of20˜40 wtppm in the single crystal particles. Accordingly, a disposaltreatment must be carried out to reduce [H] to be 7.5 wtppm or less.

FIG. 3 is a longitudinal sectional view of an apparatus for carrying outthe treament. In the figure, reference numeral 21 indicates a heatingcontainer made of carbon graphite. Around the heating container 21, aheater 22 is provided. The heating container 21, provided with theheater 22 is housed in a housing 23 made of metal. At one end portion ofthe heating container 21, in the state that the upper surface of thehousing 23 is penetrated, a particle inlet pipe 24 and a gas effluent(outlet) pipe 25 are placed side by side and are connected with theheating container 21, respectively. At the other end portion of theheating container 21, in the state that the lower surface of the housing23 is penetrated, a particle extracting outlet pipe 26 is connected withthe heating container 21. At the halfway of the particle extracting pipe26, a gas affluent pipe 27 is connected therewith.

In an apparatus of such a structure, silicon granules (diameter:0.015˜0.30 cm) prepared by the silane process are passed into theheating container 21 through the particle inlet pipe 24 and an inert gassuch as argon gas is introduced into the heating container 21 throughthe gas inlet pipe 27, while silicon granules in the heating containerare heated by the heater 22. Then hydrogen included in the silicongranules is thermodiffused or evaporated, and exhausted to the outsidethrough the gas outlet pipe 25 together with the introduced inert gas.After that, the silicon granules which have been reduced in [H] aretaken out through the particle extracting pipe 26.

In the case where [H] is reduced by the apparatus above mentioned, when[H] at the center of a granule (assuming the granule to be sphericalwith a diameter d.sub.ρ) is reduced to the extent of 13/100 of a granulepassed into the heating container 21, for example, heat treatment shouldbe carried out so as to certify the following equation (1). ##EQU1##wherein, D(T): diffusion coefficient of hydrogen atom

t: heating time [s]

T: heating temperature [K]

By observation, in the case where the heating temperature is within alimit of 700°˜1100° C., an equation D(T)=2.1×10⁻⁴ exp (-0.564 e.v./kT)[cm² /s] is satisfied.

wherein k: Boltzmann constant,

In addition, the diffusion coefficient D(T) accompanying temperaturechange is shown in FIG. 4. The diffusion coefficient of the hydrogenmolecule D(T)=9.4×10⁻³ exp (-0.48 e.v./kT) [cm² /s] is also shown inFIG. 4.

FIG. 5 is a graph showing the relationship between the left side of theequation (1) aforementioned (the abcissa axis) and [H] at the center ofa granule (provided that initial value=1, the ordinate axis). As shownin FIG. 5 A broken line, when the value of the left side of the equation(1) is set to be 0.07, for example [H] can be reduced to the extent of0.13 times its original concentration. Furthermore, at the peripheralportion of a granule, the rate of reduction of [H] is rapid comparedwith that at the center, and when the value of the left side of theequation (1) is set to be 0.07, [H] at the peripheral portion of agranule is almost 0.

FIG. 6 is a graph showing a result of an experiment about an effect bescattering, exerted by heating temperature and heating time for silicongranules, the abcissa axis and the ordinate axis showing the heatingtemperature and the heating time, respectively. The curve in the graphshows the case where the value of the left side of the equation (1) is0.07. And the symbols ◯ and show no scattering and scatteringrespectively.

As is obvious from the graph, when the heat treatment is carried outwithin the limits of the region affixed with hatching with the thresholdcurve as the borderline, [H] is reduced to 7.5 wtppm or less, therebysilicon granules with no scattering can be obtained.

On the other hand, in the case where silicon granules are prepared bythe trichlorosilane process, trichlorosilane gas is introduced on thesurface of powdered silicon seeds introduced in a bell jar, and thepowdered seeds grow into granules by means of reduction at thetemperature of 1000°˜1200° C.

As the chlorine (Cl) taken in produced granules is hard to diffusecompared with hydrogen (H), [Cl] is not reduced even when the heatingtreatment aforementioned is carried out. Accordingly, in order to reduce[Cl], it is necessary to reduce [Cl] when granules are produced.

The relationship between the deposition rate of silicon granules and[Cl] a growth experiment using trichlorosilane process, carried out bythe inventors is shown in FIG. 7. In addition, the experiment conditionsare as follows;

reacting apparatus: a similar apparatus to the one shown in FIG. 3

reaction temperature: 900°˜1100° C.

trichlorosilane / H₂ (molar ratio): 0.05˜2

total pressure: 1 atm

height of fluidized bed: 30˜180 cm

diameter of a particle: 0.05˜0.2 cm.

The straight line in FIG. 7 shows a tendency of correlation between thesilicon desposition rate and the [Cl] contents FIG. 7 shows a strongcorrelation between both of these parameters. The larger the depositionrate of silicon is, the more [Cl] is reduced. In this growth condition,[Cl can be reduced to 15 wtppm or less by making the deposition rate ofsilicon to be 0.4 μm/min. or more.

As above mentioned, silicon granules related to the method of thepresent invention can be obtained.

Next, an example of a concrete apparatus is shown in the case wheresingle crystal growth is carried out by using silicon granules relatedto the invention (silicon granules in which [H] is reduced to 7.5 wtppmor less or silicon granules in which [Cl] is reduced to 15 wtppm orless).

FIG. 8 is a sectional view of a first embodiment of an apparatus forcarrying out the single crystal growth of the invention, whereinreference numeral 1 designates a chamber, 2 designates a heat reservingwall, 3 designates a crucible, and 4 designates a heater. At the innersurface of the chamber 1, the heat reserving wall 2 is lined. Thecrucible 3 is provided the center portion of the chamber 1 surrounded bythe heat reserving wall 2. The heater 4 is provided between the crucible3 and the heat reserving wall 2 in the state of forming an air passagewith the proper gap between them.

The crucible 3 has a double construction in which a container made ofquartz is set in a container made of graphite. At the central portion ofthe bottom of the crucible 3, an upper end of an axle 3a which passesthrough the bottom wall of the chamber 1 is connected, and the crucible3 is lifted up and down by the axle 3a, while being rotated.

At the center of the upper wall of the chamber 1, a lift opening 1a forsingle crystal pulling also serves as a supply opening for ambientatmosphere gas, and a material supply opening 1b is opened at a portionaround the lift opening 1a. At the lift opening 1a, a guard cylinder 5is installed, and a material supply pipe 6a of a material supplyapparatus 6 is inserted into the chamber 1 through the material supplyopening 1b.

From the upper end of the guard cylinder 5, a chuck 5b for seizing aseed crystal 5c with the use of a lift axis 5a is hung down, and theupper end of the lift axis 5a is connected with a rotation andup-and-down mechanism (not shown). After the seed crystal 5c is broughtinto contact with into the liquid silicon inside of the crucible 3,silicon single crystal is grown at the lower end of the seed crystal 5cby rotating and raising the seed crystal 5c.

Inside of the chamber 1, at the upper surface of the heat reserving wall2, a supporting member 8 in a form of an annular ring is provided. Abulkhead member 9 is made of quartz, and consists of supporting pieces9b provided at plurality of positions spaced-apart in thecircumferential direction at an inner periphery of the supporting member8 and a cylindrical bulkhead portion 9a is supported by the supportingpieces 9b. The lower end of the cylindrical bulkhead portion 9a ispositioned at a predetermined height from the inner bottom of thecrucible 3, and is brought into contact with into the liquid silicon toa predetermined depth. The cylindrical bulkhead portion 9a divides thecrucible into two regions; i.e., an inner region and an outer circularregion concentric with each other.

A material introducing tool 10 includes a funnel portion 10a and a pipe10b connected therewith. The funnel portion 10a faces the lower end ofthe material supply pipe 6a inserted from the material supply opening1b.

The pipe 10b passes through the supporting member 8, and the lower endof the pipe 10b is in the crucible 3, facing the outer circular regionoutside the cylindrical bulkhead portion 9a.

The upper end of the material supply pipe 6a is positioned below anelectromagnetic feeder 6c of a weighing apparatus provided in a casing6b at the material supply apparatus 6 provided outside the chamber 1.The end of the electromagnetic feeder 6c is provided with a sub-hopper6d, and above the sub-hopper 6d, a main hopper 6e fixed on the casing 6bfaces therewith.

Next, explanation is given on a concrete procedure of silicon singlecrystal growth by using an apparatus of such a construction.

At first, after silicon granules related to the present invention areput in the crucible 3 as initial charge silicon materials, the crucible3 is heated by the heater 4, thereby melting the stored silicon granulesin the crucible 3. With the melting, the volume is decreased, therefore,a proper quantity of silicon granules related to the invention is addedinto the crucible 3 as charge up silicon materials.

The crucible 3 is rotated by the axis 3a supporting the crucible 3 inthe direction of an arrow, and the lift axis 5a forming a lift means islowered to soak the seed crystal 5c into the liquid silicon inside thecylindrical bulkhead portion 9a. After that, the lift axis 5a is pulledup at a prescribed speed (average speed 1.5 mm/min.) while beingrotated, and the silicon single crystal 7 is grown onto the lower end ofthe seed crystal 5c.

The silicon granules are stored in the main hopper 6e in advance as theadditional charge silicon materials. And they are supplied to the outerregion of the cylindrical bulkhead portion 9a in the crucible 3 throughthe main hopper 6e, the sub-hopper 6d, the electromagnetic feeder 6cwhere they are weighed, the material supply pipe 6a and through thematerial introducing tool 10.

In addition, from the beginning of the melting of the silicon granulesstored in the first place, to the end of pulling up the single crystal,an inert gas such as argon is introduced above the crucible 3 throughthe guard cylinder 5 from a supply pipe connected with the upper end ofthe guard cylinder 5. The inert gas passing from the upper part of theguard cylinder 5 is screened by the supporting member 8, gets to thesurface of the liquid silicon in the crucible 3 along the silicon singlecrystal 7, and is drawn out of an exhaust port 1c opened at a side wallof the lower part of the chamber 1 by an exhausting pump (not shown),through the cylindrical bulkhead portion 9a and the supporting pieces9b, the outer region of the cylindrical bulkhead portion 9a and throughan air passage formed between the heater 4 and the heat reserving wall2.

In an apparatus of the embodiment, the additional charge siliconmaterials are supplied from one position in the circumferentialdirection of the crucible 3. The relationship between the phase angleand the temperature of the liquid silicon in the crucible 3 is shown inFIG. 9. In addition, arrows in the figure show the supply position ofthe additional charge silicon materials. As is understood from FIG. 9,in this embodiment, since the silicon materials are supplied from oneposition, the temperature of the liquid silicon drops remarkably only inthe vicinity of the supply position. Accordingly, there is a possibilitythat the growth condition is disturbed in such a case.

FIG. 10 shows a sectional view of a second embodiment of an apparatusfor carrying out the method of the invention. In addition, the samereference numerals shown in FIG. 8 are used to show the same orcorresponding parts. In this apparatus of the embodiment, the additionalcharge silicon materials are supplied from plural positions in thecircumferential direction of the crucible 3.

The material introducing tool 10 consists of the funnel portion 10a anda plurality (four, for example) of pipes 10b connected therewith.Respective pipes 10b successively pass through the chamber 1, thesupporting member 8 and a bulk-head portion 9c of the bulkhead member 9.The lower ends of the respective pipes 10b are provided at the sameintervals (four lower ends, for example) in the circumferentialdirection as the pipes 10b and face the outer region in the crucible 3.A material supply apparatus for supplying the silicon materials to thematerial introducing tool 10 is not shown in the figure.

In this embodiment, the additional charge silicon materials are suppliedfrom plural positions in the circumferential direction while thecrucible is rotated. The relationship between the phase angle of thecrucible 3 and the liquid silicon temperature in such a case is shown inFIG. 11. In addition, arrows in the figure show the supply position ofthe additional charge silicon materials (in this example, four positionsat every π/2). As is understood from FIG. 11, in this embodiment, sincethe silicon materials are supplied from plural positions, thetemperature drop of the liquid silicon in the vicinity of the supplypositions is small. Accordingly, this embodiment is capable of reducingthe possiblility of disturbing the single crystal growth condition incomparison with the first embodiment.

Furthermore, in the embodiment above mentioned, the silicon granulesrelated to the invention are used as the initial charge siliconmaterials, the charge up silicon materials and the additional chargesilicon materials, however, it goes without saying that the silicongranules related to the invention may be used as any one or any twokinds of the three uses above mentioned.

As this invention may be embodied in various forms without departingfrom the spirit of an scope thereof, the foregoing embodiments aretherefore illustrative and not restrictive, since the scope of theinvention is defined by the appended claims rather than by the foregoingdescription, and all changes that fall within the scope of the claims,or equivalents thereof are therefore intended to be embraced by theclaims.

What is claimed is:
 1. A method for producing silicon single crystalusing silicon granules, comprising:preparing powdered silicon; growingsilicon granules by decomposing silane gas on the surface of saidpowdered silicon; heating said silicon granules in an atmosphere of aninert gas so as to have a residual hydrogen concentration of 7.5 wtppmor less; and growing silicon single crystal by pulling a silicon seedcrystal from a melt of liquid silicon prepared by melting said silicongranules.
 2. A method for producing silicon single crystal as set forthin claim 1, wherein in the step of growing silicon single crystal, saidsilicon granules are put in a crucible and melted, said silicon seedcrystal is brought into contact with said melt of liquid silicon in saidcrucible, and said silicon single crystal growing at an end of with saidseed crystal is pulled up together with said seed crystal.
 3. A methodfor producing silicon single crystal as set forth in claim 1, wherein inthe step of growing silicon single crystal, said silicon granules aresupplied in a crucible as additional charge silicon materials.
 4. Amethod for producing silicon single crystal as set forth in claim 3,wherein said silicon granules are supplied in said crucible as initialcharge silicon materials.
 5. A method for producing silicon singlecrystal as set forth in claim 1, wherein in the step of growing siliconsingle crystal, a bulkhead for dividing a crucible into an inner regionand an outer region is provided in said crucible in the state that bothregions communicate with each other under a surface of said liquidsilicon, said silicon seed crystal is brought into contact with saidliquid silicon in said inner region, said silicon granules are suppliedinto said outer region as additional charge silicon materials, and saidsilicon single crystal growing at an end of said seed crystal is pulledup together with said seed crystal.
 6. A method for producing siliconsingle crystal as set forth in claim 5, wherein said silicon granulesare supplied into said inner region of said crucible as initial chargesilicon materials.
 7. A method for producing silicon single crystal asset forth in claim 5, wherein said silicon granules are supplied intosaid outer region from plural positions in a circumferential directionof said crucible.
 8. A method for producing silicon single crystal usingsilicon granules, comprising:preparing powdered silicon; growing silicongranules by reducing trichlorosilane gas on the surface of said powderedsilicon, wherein the growth rate of silicon is set to more than 0.4m/min so as to have a residual chlorine concentration of 15 wtppm orless; and growing silicon single crystal by pulling a silicon seedcrystal from a melt of liquid silicon prepared by melting said silicongranules.
 9. A method for producing silicon single crystal as set forthin claim 8, wherein in the step of growing silicon single crystal, saidsilicon granules are put in a crucible and melted, said silicon seedcrystal is brought into contact with said melt of liquid silicon in saidcrucible, and said silicon single crystal growing at an end of said seedcrystal is pulled up together with said seed crystal
 10. A method forproducing silicon single crystal as set forth in claim 8, wherein in thestep of growing silicon single crystal, said silicon granules aresupplied in said crucible as additional charge silicon materials.
 11. Amethod for producing silicon single crystal as set forth in claim 10,wherein said silicon granules are supplied in said crucible as initialcharge silicon materials.
 12. A method for producing silicon singlecrystal as set forth in claim 8, wherein in the step of growing siliconsingle crystal, a bulkhead for dividing a crucible into an inner regionand an outer region is provided in said crucible in the state that bothregions communicate with each other under a surface of said liquidsilicon, said silicon seed crystal is brought into contact with saidliquid silicon in said inner region, said silicon granules are suppliedinto said outer region as additional charge silicon materials, and saidsilicon single crystal growing at an end of said seed crystal is pulledup together with said seed crystal.
 13. A method for producing siliconsingle crystal as set forth in claim 12, wherein said silicon granulesare supplied into said inner region of said crucible as initial chargesilicon materials.
 14. A method for producing silicon single crystal asset forth in claim 12, wherein said silicon granules are supplied intosaid outer region from plural positions in a circumferential directionof said crucible. .Iadd.
 15. A method for producing silicon singlecrystal using silicon granules comprising:preparing powdered silicon;growing silicon granules by decomposing silane gas on the surface ofsaid powdered silicon; heating said silicon granules in a heatingcontainer to release the hydrogen included in the silicon granules as H₂which is removed therefrom, said heating being carried out until thesilicon granules have a residual hydrogen concentration of 7.5 wtppm orless; and growing silicon single crystal by pulling a silicon seedcrystal from a melt of liquid silicon prepared by melting said silicongranules. .Iaddend. .Iadd.
 16. The method of claim 15, wherein the H₂ isexhausted to outside of said heating container. .Iaddend.